This chapter scrutinizes the process and demonstrates the value that it can make to decision-making practices. In the first instance the process will be contextualised with the spotlight falling on the legislative, policy and guidance framework. The purpose of screening is to assess whether an Environmental impact assessment (EIA) is required and the Regulations identify a number of ways in which a determination can be made. Scoping involves a negotiation between the developer, the planning authority, and, ideally, the public. It is considered a very important stage as it allows the parties to identify and clarify the issues which will be monitored later in the process. The chapter discusses scrutiny of the key stages which underpin EIA (screening, scoping, assessment of effects, mitigation and monitoring). EIA is an important tool in developing a deeper understanding of the issues at stake in planning decision-making processes. The chapter sheds some light on the context, procedures and challenges underpinning the process.